Apparatus for anchoring a cement concrete body such as a roadway onto a base of sand, gravel, soil or similar material

ABSTRACT

The invention relates to an improved method of anchoring and bonding a layer of cement concrete, primarily a roadway, onto a base of such resilient material as sand, gravel, stony soil and similar material by forming anchoring elements extending from the cement concrete layer into holes formed in the base and filled with cement concrete flowing down from the cement concrete layer before the hardening thereof. The method operates with elongated hole forming members which are forced downwards in axial direction through the not yet hardened cement concrete layer at an inclined angle to the surface of said layer and into the base to a predetermined depth and thereupon turned about their lower ends to at least vertical and preferably an opposite inclined angular position and thereupon retracted in their axial direction to be swung back to the primary angular position for beginning a new cycle of operations. A preferably travelling apparatus for carrying out the novel method is equipped with at least one hole forming member which is swingably mounted on a horizontal axis and in an articulated manner connected with power means for causing the member to perform its sequence of axial advance, turning, axial retraction, and swinging return movements with adjustable speed and pressure of advance, preferably together with a plurality of cooperating hole forming members mounted on the same horizontal axis and individually controllable as to their speed and pressure by a common program work. The travelling apparatus is equipped with means to exercise a pressure on the cement concrete layer adjacent the hole forming members to force cement concrete into the holes when formed by the members.

United States Patent ()lsson Dec. 10, 1974 Inventor:

Gunnar Otto Hugo Olsson, Vibblabyvagen l6, Jakobsberg, Sweden Filed:Feb. 22, 1974 Appl. No.: 445,034

Related U.S. Application Data Division of Ser. No. 231,297, March 2,l972,-Pat. No. 3,810,708.

[30] Foreign Application Priority Data Mar. 4, 1971 Sweden 2804/71 US.Cl 404/90, 404/116, 404/75 Int. Cl. E0lc 21/00 Field of Search 404/27,31, 72, 75, 81, 404/8-2, 116, 121, 124, 90; 172/21, 22, 91,

[56] Reierences Cited UNITED STATES PATENTS 2,649,061 8/1953l-lawkinsetal... ..111/6 3,650,332 3 1972 Dedoes 172122 FOREIGN PATENTSOR APPLICATIONS 605,687 6/1960 Italy 172/21 Primary Examiner-MervinStein Assistant Examiner-Steven A. Hawkins Attorney, Agent, orFirm-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT The inventionrelates to an improved method of anchoring and bonding a layer of cementconcrete, primarily a roadway, onto a base of such resilient material assand, gravel, stony soil and similar material by forming anchoringelements extending from the cement concrete layer into holes formed inthe base and filled with cement concrete flowing down from the cementconcrete layer before the hardening thereof. The method operates withelongated hole forming members which are forced downwards in axialdirection through the not yet hardened cement concrete layer at aninclined angle to the surface of said layer and into the base to apredetermined depth and thereupon turned about their lower ends to atleast vertical and preferably an opposite inclined angular position andthereupon retracted in their axial direction to be swung back to theprimary angular position for beginning a new cycle of operations. Apreferably travelling apparatus for carrying out the novel method isequipped with at least one hole forming member which is swingablymounted on a horizontal axis and in an articulated manner connected withpower means for causing the member to perform its sequence of axialadvance, turning, axial retraction, and swinging return movements withadjustable speed and pressure of advance, preferably together with aplurality of cooperating hole forming members mounted on the samehorizontal axis and individually controllable as to their speed andpressure by a common program work. The travelling apparatus is equippedwith means to exercise a pressure on the cement concrete layer adjacentthe hole forming members to force cement concrete into the holes whenformed by the members.

4 Claims, 9 Drawing Figures APPARATUS FOR ANCHORING A CEMENT CONCRETEBODY SUCH AS A ROADWAY ONTO A BASE OF SAND, GRAVEL, SOIL OR'SIMILARMATERIAL This is a Division of application Ser. No. 231,297, filed Mar.2, 1972, now US. Pat. No. 3,810,708, issued May 14, 1974.

BACKGROUND OF THE INVENTION This invention relates to a method ofanchoring a cement concrete body such as a roadway, for example, onto abase of sand, gravel, soil and similar material in order to bring abouta uniform distribution of cracks of contraction coming to existence inthe body in connection with the hardening of the cement concrete. Themethod comprises molding a layer of cement concrete on the base andforcing elongated, hole forming devices downwards through the cementconcrete layer and down into the base so as to cause cement concreteafter removal of the hole forming devices to flow down into the holes inthe base and when becoming hardened to form anchoring elements. Theinvention also comprises an apparatus for carrying out the novel method.

THE PRIOR ART In the co-pending patent application Ser. No. 51,794 filedon July 2, 1970, now US. Pat. No. 3,680,450, issued on Aug. 1, 1972, itis disclosedalready to force devices correYpbnding to the shape of theanchoring elements through the cement concrete layer prior to thehardening thereof and into the base, whereupon the holes or impressionsformed in this way in the base are filled with cement concrete in orderto provide a maximum of friction between the cement body and the base,whereby the cement concrete body due to the movements appearing inconnection with the hardening of the cement concrete and afterwards dueto changes in temperature accumulates in each little area around eachanchoring element stresses of such nature that a very high number offine fissures of contraction come into existence instead of one or a fewbig cracks.

However, it has been experienced that the use of hole forming deviceshaving a shape corresponding to the desired shape of the anchoringelements will not always result in well defined holes because the formedholes often are slipped together by the hole forming devices duringtheir movement in an arcuate path through the soil, causing the holes tobe filled with base material before the cement concrete has had time toflow down into the holes. Such sliding of material from the base intothe holes becomes particularly striking when the base consists of sand,and the difficulty of forming holes by means of devices of thepreviously disclosed type is especially prominent when the base or soilis stony.

THE OBJECTS OF THE INVENTION One main object of the invention is thus toprovide a method for forming holes for the anchoring elements whichsurely are filled with cement concrete irrespective of the nature of thebase material. Base material is in the following to be understand asprimarily comprised of sand, gravel, stony soil, or a base of maccadamand soil reinforced by admixed concrete.

Another object of the invention is to provide an apparatus which iscapable irrespective of the nature of the base material of forming holesof such shape that they are not collapsed by surrounding base materialbut retain their form until filled with cement concrete fromsuperimposed, not yet hardened cement concrete.

Further objects and advantages of the invention will become apparentfrom the following description, considered in connection withaccompanying drawings, which form part of this specification and ofwhich:

GENERAL PRESENTATION OF THE DRAWINGS FIGS. 1a to 1e are diagrammaticillustrations of the operation of a hole forming device.

FIG. 2 is a diagrammatic side view of a travelling apparatus equippedwith hole forming devices.

FIG. 3 is a simplified side view of a hole forming device of the typewith which the apparatus of FIG. 2 is equipped. 7

FIG. 4 is a front view of the lower portion of the hole forming deviceshown in FIG. 3.

FIG. 5 is a section following the line V-V of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The method of forminganchoring elements between a not yet hardened cement concrete body 1 anda base 2 is illustrated in FIGS. la to 1e. These figures show in asimplified manner the lower portion of a hole forming device 3 having adigging end portion or shovel 4. FIG. la illustrates the moment when thehole forming device 2 as a result of an axial displacement with apredetermined inclination to the cement concrete layer 1 with its endportion 4 has reached the surface 5 of said cement concrete layer 1. Theaxial advancement of the rod-shaped device 3 is continued until its endportion 4 has penetrated downwards to the predetermined depth in thebase 2. In the illustration of FIG. 1b this advancement movement isalmost finished. FIG. 10 shows the end portion in its final position ofaxial displacement while the device 3 with its end portion 4 as axis ofrotation has been turned upwards to a vertical position. The turningmovement which in FIG. 1 is shown to be effected clockwise is preferablycommenced only after the axial advancing displacement has been finished,but may also be started earlier.

FIG. 1d illustrates the moment when the hole forming device has beenturned further clockwise past the vertical line and an axial retractionmovement has been imparted thereto. FIG. 1e shows the moment when thehole forming device has been retracted still more and left the cementconcrete layer 1. Thereafter, the hole forming device is turnedcounterclockwise and the cycle of operations is repeated.

As will appear from the FIGS. 1c to 12, the preferably shovelformedlowermost portion 4 of the device 3 during its turning movement aboutthe lowermost point thereof with its front will displace a quantity ofbase material corresponding to the shovel surface ahead and thereby forma hole or aperture 6 which is represented in axial section. This holewill be filled in accordance with the widening of its mouth 7 bymovement of the shovel 4 with cement concrete and will be completelyfilled with concrete when the shovel 4 has been retracted. Thefilling-out of the hole 6 is facilitated by continously compressing thecement concrete layer 1 by means of a roller or a similar element asshall be explained below in more detail.

From the FIGS. to 1e it will further be understood that the lowermostportion of the shovel 4 during its turning movement forces base materialto form a bank 8. This bank 8 results in that the spacing between theupper'surface of the base, i.e. the top ridge of the bank 8 and thesurface of the cement concrete layer will be reduced adjacent eachanchoring element 9, and thereby a fracture indication for release offissures of contraction in the body adjacent the anchoring element iscreated.

FIG. 2 shows in a simplified manner a travelling apparatus or truck 10intended to be advanced in the direction of the arrow A, e.g. by its owndriving means, over the not yet hardened cement concrete layer 1. Thetruck 10 has in the shown embodiment supporting rollers 11 and 12engaging the ground, of which the rear roller 11 is assumed to bepivotable about a vertical shaft 13 to render possible the steering ofthe truck. The front roller 12 brings about the afore-mentionedcompression of the cement concrete layer in order i.a., to make surethat the holes formed in the base are filled with cement concrete. InFIG. 2 there are illustrated three hole forming devices 3, 3a and 3b,which are mounted swingably about an axis 14, which extends at a rightangle to the direction of drive A. The three hole forming devices aremounted spaced from one another in the direction of the axis 14 and willthus form three mutually parallel rows of holes in the base 2. Even ifonly three hole forming devices have been shown, any desired number canbe mounted depending on the breadth of the base 2 to be provided withanchoring holes.

All three hole forming devices 3 operate as described in connection withthe FIGS. la to 1e; but in order to bring about various hole patternsthey may be arranged to become operative at mutually different momentsand also be driven with mutually different speeds.

In FIG. 2 the hole forming device 3 is thus assumed to be in the workingpositionaccording to FIG. 1d, whereas the devices 3a and 3b are in theworking positions corresponding to FIGS. 1c and 1b, respectively. Thespacing between two adjacent holes in each row will depend on theworking speed of the device forming this hole, i.e. of the time spent toperform a working cycle according to th FIGS. In to 1e. The swingingmovement which each hole forming device performs about the upper pivotaxis 14 is carried out on actuation by a driving device diagrammaticallyindicated at 15. This driving device 15 may e.g. consist of a hydraulicmotor having a reciprocating piston rod 16 for each of the hole formingdevices 3, 3a, 3b. The piston rod 16 is articulately connected to itscooperating hole forming device at 18.

FIG. 3 shows more detailed though still diagrammatically a hole formingdevice 3 of the type employed in the apparatus according to FIG. 2. Aholder member 21 is pivotably mounted on the axis 14. Said holder member21 carries a hydraulic cylinder 19 having a piston 20 formed integrallywith a prolongation constituted by the rod-shaped hole forming device 3and terminating with a shovel 4. The piston 20 is by the cylinder l9imparted an axially directed movement towards the shovel 4 during thepressing down thereof into, or retraction from, the cement concretelayer 1 and the base 2. The turning movement of the hole forming deviceabout the lowermost point of the shovel and the simultaneous pivoting ofthe holder member 21 about the axis 14 during the continuous travel ofthe truck is. as mentioned already, brought about by the piston rod 16.It should be observed, however, that a direct driving by means of thepiston rod 16 is not absolutely necessary when the shovel is inside thebase 2 since an automatic turning movement can be brought about by theown motion of the truck. However, when the device 3 has been retractedand is to be returned to commence a new working cycle from the positionaccording to FIG. la, a driving force must be supplied from the pistonrod 16.

The cylinder 19 may be devised to allow a certain return movement of thepiston 20 from its most projected position in order to compensate forthe reduction of the spacing between the outermost point of the shoveland the axis 14 when the hole forming device approaches the verticalposition. A compensation for this reduction of the distance can also bebrought about by a resilient mounting in bearings of the axis 14.

Both the cylinder 15 and the cylinder 19 are suitably controlled by aprogram unit 22 of conventional kind. The program unit controls thesupply of a pressure fluid such as oil to and from the cylinders throughpipes 23, 24 and determines in this way axial movements and turning andpivoting movements, respectively, of the individual hole formingdevices. Preferably the program unit is operated with punched cards soas to enable the forming of various hole patterns in response to thenature of the base, and preferably the program unit is further devisedto feed oil to each cylinder 19 with a pressure corresponding to thedensity of the base so as to ensure that holes with a predeterminedminimum depth are formed in the base. In case that the density of thebase varies, which is the most usual case, the force is determined withregard to the highest density and the program unit is adjusted inaccordance thereto. In this way the depth of the holes will beautomatically adapted to occurrring variations in density and correctanchoring or bonding will be obtained.

FIG. 4 shows a front view of a suitable shovel 4 and FIG. 5 a sectionthrough said shovel. The shape and the size of the lower, hole-formingportion of each device may, however, be varied in various manners andsuch shovel may have a purely rectangular contour or a triangular onewith a downward directed point.

If a further concrete layer shall be molded on the layer 1 and a bondingof the uppermost layer with the underlying layer or layers is desired,the same technique as described above may be applied, the holes beingformed in the cement concrete layer 1 prior to the hardening thereof.

While one more or less specific embodiment of the method and theapparatus according to the invention has been described and shown, it isto be understood that this is for purpose of illustration only and thatthe invention is not to be limited thereby, but its scope is to bedetermined by the appended claims.

What is claimed is:

1. An apparatus for anchoring a cement concrete body in a base of sand,gravel, soil, or similar material to bring about a uniform distributionof cracks of contraction coming to existence in the body in connectionwith the hardening of the cement concrete, said apparatus including atleast one rod-shaped hole forming device (3), characterized in that thehole forming device is articulately fixed to an apparatus adapted totravel on the cement concrete layer (1), that driving means (22, 15, 19)are devised to adjust the hole forming device (3) with the longitudinalaxis thereof inclined to the upper surface of the cement concrete layerand to impart to the hole forming device an axial, downwards directedmovement and to drive said device through the cement concrete layer (1)into the base (2) to the depth corresponding to the density of the baseand then to impart to the device a turning movement about the lower endof said device and after that the longitudinal axis of said hole formingdevice has been turned to a predetermined extent to retract said deviceout of the base and the cement concrete layer.

2. The device as claimed in claim 1, characterized in that the lower endof the hole forming device (3) has the shape of a shovel (4).

3. The device as claimed in claim 1, characterized in that the drivingmembers (19, 20) for axial displacement of the hole forming device (3)are devised to exert an axial force in response to the density of thebase (2).

4. The device as claimed in claim 3, characterized in that said axialforce responds to the maximum density ofthe base.

1. An apparatus for anchoring a cement concrete body in a base of sand,gravel, soil, or similar material to bring about a uniform distributionof cracks of contraction coming to existence in the body in connectionwith the hardening of the cement concrete, said apparatus including atleast one rod-shaped hole forming device (3), characterized in that thehole forming device is articulately fixed to an apparatus (10) adaptedto travel on the cement concrete layer (1), that driving means (22, 15,19) are devised to adjust the hole forming device (3) with thelongitudinal axis thereof inclined to the upper surface of the cementconcrete layer and to impart to the hole forming device an axial,downwards directed movement and to drive said device through the cementconcrete layer (1) into the base (2) to the depth corresponding to thedensity of the base and then to impart to the device a turning movementabout the lower end of said device and after that the longitudinal axisof said hole forming device has been turned to a predetermined extent toretract said device out of the base and the cement concrete layer. 2.The device as claimed in claim 1, characterized in that the lower end ofthe hole forming device (3) has the shape of a shovel (4).
 3. The deviceas claimed in claim 1, characterized in that the driving members (19,20) for axial displacement of the hole forming device (3) are devised toexert an axial force in response to the density of the base (2).
 4. Thedevice as claimed in claim 3, characterized in that said axial forceresponds to the maximum density of the base.